MGD S4 - DNA replication, Cell division and Inheritance Flashcards
What is the role of the cell cycle?
Mitosis division used in growth and repair
Contains several key checkpoints to prevent improper cell division
What are the stages of the cell cycle? (Names only)
G1
S
G2
Mitosis
What’s occurring during S phase of the cell cycle?
Chromosomes duplicate to form classical X shape (2 chromatids)
At happens in G1 phase of the cell cycle?
Cellular content replication
What happens during G2 phase of the cell cycle?
DNA is checked for errors and corrected
At happens during the mitosis phase of the cell cycle?
The cell divides creating two genetically identical daughter cells.
Define genotype
The genetic makeup of an individual
Can also refer to a specific genetic loci
Define phenotype
All observable expressed traits as a result of genotype
Can also refer a specific trait arising from a single genetic loci
Are gametes haploid or diploid?
Haploid
What environmental factors may affect genotype and phenotype?
Radiation Mutagens Chemicals that affect cell growth Diet Lifestyle (phenotype only) Trauma (phenotype only)
How does meiosis I differ from mitosis?
Instead of lining up along the equator single file, they line up in homologous pairs and are split into two sets of full (2 chromatids) chromosomes.
What sort of genetic disease affects 25% of two carriers offspring?
Give an example
Autosomal recessive
Cystic fibrosis
Name the three types of sex linked inheritance.
X linked dominan
tX linked recessive
Y linked
Define the term ‘allele’
Refers to the different forms of a gene. Every individual has two alleles of the same gene, can either be the same or different.
Define the term ‘gene’
A unit of heredity, length of DNA that codes for a protein as well as the necessary sequences for it’s expression such as promoter and terminator sequences and introns
What is autosomal inheritance?
Inheritance of a gene on a non sex linked chromosome (autosome)
What is meant by co-dominance in reference to alleles/traits?
Give an example of co-dominance
Both alleles are expressed in the phenotypic trait of heterozygotes.
Eg. AB blood type
Explain the basis of co-inheritance of genes.
Genes on the same chromosome are likely to be inherited together
However the process of crossing over in meiosis will separate genes previously on the same chromosome.
Additionally, genes located close to one another on the same chromosome are said to be LINKED, less likely to be separated in crossing over.
Genes further away from each other more likely to be separated. Behave almost like unlinked.
What sort of genetic disease effects one person of every generation?
Give an example.
Autosomal dominant
Marfan’s syndrome
What is sex linked inheritance?
Inheritance of a gene on the X or Y chromosome
Haemophilia is an example of what type of genetic disease?
X linked recessive
What sort of genetic disease only affects males?
Y linked, passed from father to son.
Explain what is meant by ‘dominance’ of an allele/trait.
The phenotypic trait is expressed in homozygotes and heterozygotes
Explain what is meant by the term ‘recessive’ for alleles/traits.
Phenotypic trait appears only in homozygotes
